28th January, 2023 Environment
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Context: Kelp forests — underwater ecosystems formed in shallow water by the dense growth of several different species known as kelps — are declining because of climate change, showed a new study.
- Kelp populations at equatorward-range edges are particularly vulnerable to climate change as these locations are undergoing warming at or beyond thermal tolerance thresholds, the study published in the journal Nature
- Due to this, the unique adaptive or evolutionary genetic diversity that the rear-edge populations (populations in warm, low-latitudes) may contain is also under threat due to rapid warming.
- Ecklonia radiata, the dominant and most widely distributed Laminarian kelp in the southern hemisphere, rapidly succumb to warmer temperatures in spring and summer when temperatures exceed 27 degrees Celsius.
- New populations were found in shallower and cooler winter months with temperatures around 20°C, the findings indicated.
- Contemporary climate change is threatening the high and unique genetic diversity found among eastern Australian low-latitude range-edge populations, with warming causing declines of radiataalong this coastline
- Kelp can sometimes persist at lower latitudes, aided by cool water upwelling or in deep-water refugia where they are protected by thermocline (the transition layer between the warmer mixed water at the surface and the cooler deep water below)
- Identification of these refuge areas (a location which supports an isolated or relict population of a once more widespread species) is vital to ensure important genetic diversity is protected and to understand how extant and past climates shape species distribution and evolutionary diversity.
About Kelp Forests:
- Kelp forests are under water areas with a high density of kelp, which covers a large part of the world's coastlines.
- They are recognized as one of the most productive and dynamic ecosystems on Earth.
- Smaller areas of anchored kelp are called kelp beds.
- Kelp forests occur worldwide throughout temperate and polar coastal oceans.
- In 2007, kelp forests were also discovered in tropical waters near Ecuador.
- In context, algal kelp forest combined with coral reefs account for less than 1% of global primary productivity.
- Physically formed by brown macroalgae, kelp forests provide a unique habitat for marine organisms and are a source for understanding many ecological processes.
- Over the last century, they have been the focus of extensive research, particularly in trophic ecology, and continue to provoke important ideas that are relevant beyond this unique ecosystem.
- For example, kelp forests can influence coastal oceanographic patterns and provide many ecosystem services.
- However, the influence of humans has often contributed to kelp forest degradation.
- Of particular concern are the effects of overfishing nearshore ecosystems, which can release herbivores from their normal population regulation and result in the overgrazing of kelp and other algae.